Baby straining to poop

Shampree • Mom of 1 daughter and 1 son! Angel mommy of 1 💙
I have called my Dr about my son straining to poop for about 6 days now. I called to make an appt to be seen last week and they said that since he is breastfed, to just give him 1oz apple or prune juice mixed with nursery water and see if that will make him have a bowel movement. 24hrs later he still had not had a bowel movement. My mom said to try a rectal thermometer and hold it for a few seconds and then remove it. That worked wonders. He did about 3 poopy diapers back to back and nothing since then. He still has been straining all day everyday but he has not had a bowel movement in 3 days now, only passing gas. Every time i call the Dr they tell me to give him juice. He has an appt on Friday. Should i wait until his appt or take him to the ER now to help with this???